Many materials, notably fluids such as milk or fruit juices, are put up in sealed containers for transport and storage prior to use when the container is opened and the contents discharged. Many forms of containers are used for this purpose, but one form is a thin walled carton made from a thin card or plastic sheet material and having a generally squared or rectangular cross-section and a cuboid or brick-like overall shape. The contents of such a container are typically fed to the container through an open top end of the container, the other end being having been closed by folding over the basal portion of the side walls to form a boxed end to the container. When the desired amount of material has been fed to the container, the open top of the container is closed by forming transversely directed V folds in the upper portions of two opposed side walls, with the apexes of the Vs directed inwardly towards one another. This has the effect of bringing the top portions of the other two side walls of the container together to form a tented top to the container having a ridge lying along the line of indentation of the V folds. The ridge is then heat sealed or otherwise processed so as to secure together the opposed faces of the upper portions of the V folded and other side walls in a single linear transverse strip seal closure to the container, at least the major portion of the closure being located within the overall cross-sectional plan area of the container.
The sealed ridge is often then folded down about a transverse fold line located extending across approximate-ly the midpoint of one of the side walls of the tented top, so as to form a flat boxed end to the container. In some forms of such a closure, a tape which can be wire-reinforced is included in the line of the ridge, for example during folding over of the ridge material. This tape extends beyond the ends of the ridge to provide extensions which can be bent over to secure the folded down ridge in position by engaging the free ends of the tape under the lip formed along the edge of the boxed end where the V folded portion of the container wall is indented. Alternatively, the free ends of the extensions can be adhered or otherwise secured to the side walls of the container once the ridge has been folded down to form a boxed end to the container.
For convenience, the following terms will have the following means herein:
boxed end openable containers are containers of the above described general type and will be referred to herein as such containers; PA1 ridge seal will be used to denote the transverse linear seal between the opposed faces of the top end portions of the side walls of the container; PA1 ridge will be used to denote the exposed top edge of the ridge seal or the edges of the wall material which has been brought together prior to forming the ridge seal; PA1 ridge structure will be used to denote the structure formed by bringing together the top end portions of the gabled and tent side walls of the container and which are secured together by adhesion between opposing faces at the interface between those opposing faces to form the ridge; PA1 gabled end will be used to denote the structure formed at the top end of the container by indenting the upper portions of two opposed side walls of the container to form the ridge to that end of the container; PA1 tented end will be used to denote the end of the container with the ridge in the raised position either before or after forming the ridge seal; PA1 gabled side walls will be used to denote the upper portions of the two opposed side walls of the end of the container which have been indented by forming a V or other axial fold in the upper portion of the side wall so that the wall is collapsed laterally inwardly to form the gabled end to the container; PA1 tent side walls will be used to denote the two opposed side walls of the sealed top which extend between the gabled side walls of the gabled end of the container; PA1 wet wall will be used to denote a wall of the container which is to be in contact with the contents of the container, including the upper portions of such walls which are to be incorporated into the ridge seal; PA1 dry wall will be used herein to denote a wall of the container which is not in contact with the contents of the container, including the upper portions of such walls which are to be incorporated into the ridge seal. PA1 a. a shank member having one or more foot members extending laterally of the distal end of the shank, the foot member(s) being secured to an external face of the ridge seal and/or an adjacent tent side wall; and PA1 b. a proximal end to said shank member having means by which a user may grasp the shank member and apply tension thereto. PA1 a. a shank member extending between a proximal end adapted to be grasped by a user and distal end adapted to be secured to a tent side wall and/or a side wall of the ridge seal of the sealed container or a blank for use in the manufacture of such a container; PA1 b. one or more foot members extending transversely and substantially symmetrically from said distal end of said shank member; PA1 said pull tab being made from a sheet material having a surface which can be fused with or otherwise adhered to the material of said container wall or ridge. Preferably, said foot is provided with an axial extension thereto and the pull tab is made from a laminate of a polyalkylene on a polyester.
To open such a boxed end openable container, the seal at the interface between the opposing dry wall surfaces of the V fold at one end of the linear ridge seal is separated. This forms a pair of wings in the gabled end so that the plan view configuration from above of the ridge seal to the container adopts a Y shaped configuration in place of a single line seal. The top edges of the wings forming the head of the Y remain sealed together. The wings are then bent backward to lie in line with each other, ie. so that the plan view configuration from above of the ridge seal adopts a T shaped configuration with the wings forming the head of the T. The free ends of the wings are then pressed inwardly towards the centre line of the upright of the T to apply a separating force transverse to the line of the seal at the intersection of the head and the upright of the T. This causes the seal between the opposed faces of the wet walls at the top edges of the container to separate at this intersection and to form an opening through which the contents of the container can be discharged. In some cases it may be desired to bend the wings beyond the in-line configuration so as to enhance the separating force applied to the seal at the intersection upon the application of pressure to the free ends of the wings.
However, separation of the seal is often incomplete and/or the wings collapse so that the user cannot continue to apply the separating force to the seal. It is therefore usually necessary for the user to insert a finger tip into the initial opening formed at the intersection to assist full separation of the seal between the faces of the wet walls to allow the V fold in the wall of the container to be unformed and then inverted to form a spout outlet to the container.
In many cases the initial separation of the seal between the wet walls at the intersection is insufficient to form an aperture into which the user can insert a finger tip. It is then necessary for the user to pinch the dry wall material in the unfolded gabled end wall of the container in the region of the V fold and try to pull the wall outwardly to assist separation of the seal. Such separation of the seal may occur abruptly, causing spillage of the contents of the container, and the need for such additional operations to separate the ridge seal is inconvenient.
Notwithstanding these problems in forming the opening to the container, the boxed end openable container provides a simple and effective container for the storage and transport of a wide range of fluids and remains widely used.
Many attempts have been made to resolve the difficulties in opening such containers. Thus, it has been proposed in British Patent Application No 2 253 608 A1 to form a slit in one of the gabled end walls and to apply a removable seal strip over the slit. The container is opened by separating the ridge seal and bending the wings of the ridge seal backwards to the T configuration as described above for a conventional such container. This has the effect of unfolding the gabled end wall and of exposing the seal strip. Removing the seal strip not only exposes the slit, but also folds the gabled end wall outwardly so as to form a spouted opening to the container through which the contents of the container can be discharged. A pull tab can be applied externally to the gabled end wall axially below the seal strip which can also be used to aid deployment of the gabled end wall.
It has also been proposed in British Patent No 1 190 131 to provided two pull tabs, one at each edge of an adhesive tape which is applied over a line of weakness in a gabled end wall of the sealed container. The end of the ridge seal is separated and the wings of the ridge pushed backwards to the T configuration as with a conventional such container to unfold the gabled end wall. The adhesive tape is removed by pulling on either or both of the pull tabs. Removal of the tape causes rupture of the gabled end wall material along the line of weakness and deploys the severed wall as a spout outlet to the container.
Such proposals require the formation of a slit or line of weakness in the wall of the container. This can result in accidental premature rupturing of the container wall as well as requiring the addition of extra components during the manufacture of the sealed container.
It has been proposed in U.S. Pat. No. 4,821,950 to provide the ridge seal with a string pull which is located between opposed faces of the wet walls of the container and extends into the container. Application of tension to the exposed end of the string pull causes the string to move along the line of the seal to separate the opposing wet wall portions of the ridge seal from one another and to deploy the gabled end wall as a spout. Such a device suffers from the problems of accurate location and securing of the pull string within the ridge seal and of contamination of the contents of the container as they are discharged due to contact with the exposed portion of the pull string.
It has also been proposed in U.S. Pat. No. 4,883,222 to form an external pull tab by axially extending the material from which the gabled end wall is to be formed and folding over that extension so that it lies within the gabled end structure. To open such a container, the ridge seal is partially separated to the T plan configuration as with a conventional such container. This exposes the free end of the extension of the gable end wall and application of tension to that free end applies a separating force to the ridge seal to separate the ridge seal at the head of the T and deploy the gable end wall as the spouted outlet to the container. However, the strength of most materials from which the container is constructed is too low to survive the stresses imposed on the extension and the extension tears along the line of the ridge in the head of the T before the seal is separated. If the strength of the ridge seal is reduced to permit it to separate before the wall material tears, the container is liable to catastrophic premature rupturing of the ridge seal.
This patent and U.S. Pat. No. 4,874,126 also describe an alternative version in which a separate pull tab is secured to the external face of the top portion of a gable end wall and the foot of the pull tab incorporated into the ridge seal between the opposing dry wall face of the V fold. The pull tab is exposed when the ridge seal in the gabled end is partially separated to adopt the T configuration as described above. When the pull tab is pulled, it should cause the ridge seal in the head of the T to separate. However, the tension required to separate the ridge seal is usually far greater than the separation force of the adhesive or other bond by which the pull tab is secured to the external face of the gabled end wall. Therefore, the pull tab separates from the ridge material before any separation of the ridge seal itself takes place. Such designs are therefore impractical. Reduction of the strength of the ridge seal to avoid separation of the pull tab from the wall material will again lead to catastrophic premature rupturing of the ridge seal.
The above proposals provide means for separating the ridge seal within the gabled end structure of the sealed container and require that the seal between opposing dry walls of the indented gable end at one end of the linear ridge seal first be separated to form the wings described above so that the linear seal adopts the T configuration before the seal between the wet faces in the head of the T can be separated. This is cumbersome and requires a number of operations to be carried out.
It has been proposed in British Patent Application No 2 010 212 A1 to apply two pull tabs within the end portion of the ridge seal. These pull tabs are pulled laterally to separate the opposed faces of the wet walls in the ridge seal whilst in the linear configuration without the need to form the ridge seal into a T configuration. However, such an assembly requires that the manufacture of the container be modified to permit the ends of the pull tabs to be inserted into the open end of the container during manufacture and held accurately in position at one end of the length of the ridge seal during its formation. Furthermore, a gabled end structure is not formed in this end of the ridge line of the container and the ridge extends beyond the side of the container. This protruding portion of the ridge requires to be folded down around the top corner of the sealed container against a side wall of the container to form a boxed end suitable for storage and transport. This requires extensive modification of the machinery to assemble, fold and seal the container and to fold the resultant sealed container.
It has also been proposed in U.S. Pat. No. 5,067,613 to provide one of the tent side walls of the tented end of the container with a tear out portion having a pull tab which extends beyond the line of the ridge seal. The tear out portion carries with it an accordion fold of material which has been incorporated within the interior of the container. As the tear out portion is pulled laterally away from the line of the ridge seal by the pull tab, the tent side wall of the container ruptures to allow the accordion fold to unmake so as to deploy the folded material as a spout. After the desired amount of the contents of the container has been discharged through the resultant spouted aperture, the aperture can be closed by reforming the accordion folds so as to collapse the spout against the remainder of the tent side wall of the container. Part of the accordion fold engages under the lip of the remainder of the tent side wall to latch the accordion fold in position. Such a structure is complex and adds considerably to the cost of the container. Furthermore, since the upstanding pull tab which is required to enable a user to deploy the spout is exposed to dirt and other contamination during storage and transport of the container prior to use, contamination of the contents of the container as they flow over the spout will occur. This proposal relies upon rupture of the tent side wall and does not cause any separation of the ridge seal itself.
Despite all these earlier proposals, no satisfactory solution to the problem of opening a conventional boxed end openable container has yet been found and none of these earlier proposals have been adopted in practice. Present proposals for providing discharge means to a such container rely upon the insertion of a plastic component through an aperture in a tent side wall, which component has a screw or snap lid to a bore through the component to provide a re-sealable outlet to the container. Such a component add costs and complexity to the manufacture and filling of the container and does to require any separation of the ridge seal of the sealed container.
We have now found that such a container can be readily opened by applying a separation force laterally to the ridge seal whilst in its linear configuration in the region of the opposed apexes of the V folds and separating the opposed faces of the wet walls in this region of the ridge seal laterally from one another. Surprisingly, this method of opening the container is remarkably easy to perform and is less prone to partial separation of the ridge seal than the previous methods which open the seal within the gabled end structure of the container. Furthermore, the method of the invention does not require complex additional components or changes to conventional container assembly, filling and closing techniques or machinery. In a particularly preferred embodiment, the lateral separation force is applied to the linear ridge seal by means of a pull tab secured externally to a tent side wall and/or to the side wall of the ridge construction. The pull tab can readily be incorporated into the structure of the container with little or no modification to the container manufacturing and filling processes, notably where the pull tab is applied to the flat blank of card or plastic from which the container is to be formed. Thus, the invention can be applied to a container which is assembled, filled and sealed using conventional techniques and machinery.